Richard Osman hosts the final round of the quiz for gifted youngsters. From the hundreds who applied to take part, only five have made it to this last stage. First, each of them will be tested with degree-level questions on their chosen specialist subjects, which are epidemiology, eukaryotic cell biology, cryptoanalysis, the periodic table, and the physics of black holes. The two highest scoring contestants will then go on to a head-to-head quickfire round to determine who will be taking home this year's Child genius trophy. Last in the series.